1. Field of the Invention
The present invention relates to an epoxy resin composition, and more particularly to hardening agents and hardening promotor for epoxy resin composition.
2. Description of the Prior Art
There have been known a number of hardening agents for epoxy resin, such as polyfunctional aromatic amine, dicyandiamide, acid anhydride, BF3 complex, etc. In the prior art, Japanese Patent Publication No. 52-92280 teaches BF.sub.3.amine complex, Japanese Patent Publication No. 53-90400 teaches imidazol derivative, Japanese Patent Publication No. 53-114900 teaches a complex of organic amine and Lewis acid or Brensted acid, Japanese Patent Publication No. 53-121825 teaches five (or six) numbered heterocycle amine and Japanese Patent Publication No. 54-25999 teaches amine carbonate. However, such hardening agents and hardening promotor as mentioned above were not able to satisfactorily improve the heat resistance of the hardened epoxy resin obtained. Due to such disadvantage, a circuit substrate made of the aforementioned epoxy resin hardening agent barely sasisfies the requirements of highly advanced circuit techology. More specifically, the highly increased wiring density on the circuit substrate demands extremely high heat resistance in the material. The existing epoxy resin does not provide such high heat resistance, and therefore improvements have been needed on this aspect. In addition, the epoxy resin product containing the aforesaid hardeners was short in gelation time, and has other drawbacks, such as the difficulty in handling, the occurrence of gelation during storage.